This is a mantra to Durga, in the form of Goddess Kātyāyani. By chanting this mantra, negativity dissolves around us and within us, including our vices and character flaws.
Śrī Durgā Gāyatri Mantra
Om Kātyāyanāya vidmahe
Tanno durgiḥ pracodayāt
May we contemplate the daughter of Kātyāyana [the Goddess Kātyāyani]
May we meditate upon the Virgin Goddess
May the Goddess Durga illuminate us